Presentation of quantitative data
Cards (10)
- Levels of data:
- Nominal- counting frequency, how often.
- Ordinal- data that can be ranked/ put into order (tends to be a whole number).
- Interval- standardised measurements where the distance between each value is known.
- Set out the data as either:
- Raw data- un-analysed
- Treated data- eg mean or range
- Bar Chart:
- Compares classes or groups of data (categories), ie nominal data.
- Bars don't touch as they're not related & categories are not in a specific order.
- Pie Chart:
- Shows frequency of category by percentage.
- Histogram:
- Shows distribution, vertical bars, bars touch, bars represent frequencies.
- All frequencies are represented even if frequency= 0.
- Shows ordinal data or continuous- this means numerical & ordered.
- Frequency polygon (line graph):
- Similar to histogram & shows distribution.
- Shows ordinal data or continuous- means numerical & ordered.
- Allows 2 or more frequency distributions to be shown on same graph.
- Scattergraph:
- Visual representation of relationship between 2 variables.
- Used to find out correlation.
- Distributions:
- Similar to histogram, but with a curved line that would join to the centre top of each bar.
- Allows us to see an overall pattern or distribution in a large set of data.
- Normal Distribution:
- Equally weighted on either side of the centre- so symmetrical.
- Forms a bell-shaped curve & the mean, median & mode all occupy the same central point on the curve.
- Skewed Distributions:
- When a distribution leans to one side rather than being central.
- A positive skew (right foot)= where the majority of distribution is on the left, leaving the mean pulled towards the right.
- Mode always remains at the highest point. Median pulled slightly right, mean pulled furthest right.
- A negative skew (left foot)= where the majority of distribution is on the right leaving the mean pulled towards the left.
- Mode remains at the highest point, median pulled slightly left, mean pulled furthest left.